Compressor unloader



C. W. METZGAR COMPRESSOR UNLOADER June 8 Filed Nov. 5. 1925 HAS ATTO E} v f INVEVTOI. mesa-alum! Patented June 8, 1926.

UNITED STATES 1,588,257 PATENT OFFICE.

CHESTER w. KETZGAB, OF EASTON, PENNSYLVANIA, ASSIGNOB T0 INGERSOLL-RAND OI JERSEY CITY, NEW JERSEY, A CORPORATION OF'NEW JERSEY.

OOIPBESSOB UNLOADEB.

Application filed November 3, 1925. Serial m. 88,495.

This invention relates. to compressors, but more particularly to a simple and cheap unloading device for the compressor, particularly adapted for double acting c linders for unloading the compressor step by step. The object of the invention is to permit successive unloading in steps by means of one clearance chamber which is also utilized as a by-pass between the ends of the cylinder for complete unloading.

Further objects of the invention will hereinafter appear and the invention is shown in one of its preferred forms in the accompanying drawings, in which- Figure 1 is a diagrammatic side elevation partly in section and partly broken away of a-double actin compressor cylinder and automatic regu ator, and

Figure 2 is a transverse sectional elevation on the line 22 of Figure 1 looking in the direction of the arrows.

Referring to the drawin the cylinder A iseprovided with a double acting piston B driven from any suitable motor or engine and the cylinder is provided with suitable inlet and discharge valves C and D indicated diagrammatically as of the plate type. Air enters at the inlet E and is dis- 0 arged through the discharge connection .F to the receiver G.

A by-pass connection H from one end of the cylinder to the other is of suflicient capacity to form a clearance chamber and is,

controlled by the clearance valves J and K controlling the valve openings L and O respectively and operatin in the valve cylinders P and Q, connecte by the pi as R and S to the automatic regulator T 0 any suitable ty e controlled by receiver ressure led to the regulator by the pipes .V'and W. The construction and arrangement of the regulator is such that upon a predetermined increase of receiver pressure, first,-

one clearance valve J is opened to partially unload the compressor due to the capacity of the clearance chamber H, and upon a further increase of receiver pressure the clearance valve K is automaticall opened. thus opening the clearance cham er Hto both ends of the cylinder and forming a ,bypass for complete pnloading. Although I have only shown two steps of unloading, it is to be understood that a greater number ofsteps may be provided, if desired, by

means of intermediate clearance chambers.

The regulator T comprises a casing X having a diaphram Y, and the receiver pipe V supplies pressure to the diaphram chamber a. A pin 12 in the guide a, which bears on the diaphram, supports a weighted lever e pivoted at the point f to a projection g on the regulator casing X. An auxiliary and 70 controls ports and passages leading to the main operating valves 0 and p which reciprocate in the valve chambers g and 1', and these valve chambers are constantly open to receiver pressure between the heads 8 and t of the main valves by means'of the connection u from the diaphram chamber a opening into the chambers or spaces 9 and r by means of theports 'v and 'w respectively. The valves 0 and p are provided with shoes m and y controlling the ports 3 and 4 in the regulator.

The receiver pipe W constantly supplies pressure at the point 5 to the regulator between the heads j and is of the pilot valve h and in full load position of the regulator the pilot valve is at the lowermost point of its travel the drawing showing the pilot valve in iigure 1 raised through onestep due to an increase of receiver pressure to efiect its movement so that the clearance valve -J is open, but under normal .con'divalve or pilot valve h having the heads 7' tions both clearance valves will be closed and both passages 6 and 7 in the regulator valve casing X will be 0 ened to receiver pressure from the pipe so that both main valves 0 and 12 will be in their right end 'positions. In such case the heads '8 of the valves 0 and p will be opened to atmosphere through the passages 8 and 9 and the open end 10 of the pilot valve casing. Receiver pressure from the valve cham bers and 1- will then pass through the ports 3 and the pi es R and S respectively to the clearance va ve cylinders P and Q, to hold the clearance valves closed.

Upon an increase of receiver ressure to a predetermined degree, for. the rst step of unloading the lever e will be raised, raising the ilot valve k to the position indicated in Figure 1. In such case" the main valve.,p will be moved to the left due to the release of pressure at the left hand end through the passage 7 which is then opened to atmosphere through the atmospheric port 12 in t e pilot valve casing, receiver pressure being admitted through the passage 9 to the ends of the cylinder.

to open due to the pressure in'the cylinder,

thus partially unloading the compressor to any desired degree depending upon the capacity of the clearancechamber H. A

further increase of receiver pressure to a predetermined degree will raise the lever 6 still further and the main valve 0 will be thrown to the left and the pipe S will be placed in communication with atmosphere through the atmospheric port 14 relieving the pressure behind the clearance-valve K and causing the clearance chamber H to become an open by-pass connection between Obviously this regulator may be operated by hand instead of automatically.

I claim:

1. In a compressor unloader, the combina tion of a double acting cylinder and piston, inlet and discharge valves for the cylinder, a by-pass connection from one end of the cylinder to the other forming a clearance chamber, and clearance valves for each end of the cylinder controlling said clearance chambers, whereby the compressor may be unloaded in' successive step s. v 2. In a compressor un oader, the com- 'ber, and the opening-of both valves completely unloads the compressor due to the open by-pass connection between the ends of the cylinder..

. 3. In a compressor unloader, the combination of a double acting cylinder and piston, inlet and discharge valves for the cylinder, aby-pass connection from one end of the cylinder to the other forming a clearance chamber, automatic clearance valves for each end of the cylinder responsive to receiver pressure and controlling said clearance chamber, whereby the opening of one valve partially unloads the compressor due to the added clearance chamber, and the opening of both valves completely unloads the compressor due to the open by-pass connection between the ends of the cylinder, and an automatic regulator for controlling said clearance valves.

In testimony whereof I have signed this 05 specification. 

